In the study by Holmøy et al from Norway (Holmøy et al., 2019), a surprising positive correlation of sNfL and 25‐hydroxyvitamin D at the study baseline was found in contrast to previously reported association of high serum 25‐hydroxyvitamin D and low CSF‐NfL in Swedish MS patients published by Sandberg et al. This evidence concerns the gene NEFL and myeloid sarcoma.